Modulation schemes for visible light communications

Visible light communication (VLC) is one of the most recent technological breakthroughs in wireless communications and it is expected to contribute significantly on future generations of mobile communications. The fundamental feature of VLC is the use of visible light spectrum to transmit data along with the traditional use for illumination. However, this requires, among others, rather fast modulation schemes of optical light sources with dimming support. In this review, we analyze the most important modulation schemes used in VLC systems and provide useful insights on their characteristics. To this end, we also investigate the data rate capabilities of each scheme along with a detailed evaluation of their pros followed by discussions and suggestions for compensating for the latter. In addition, flickering and dimming solutions based on each modulation scheme are thoroughly discussed, while new modulation techniques, such as the Asymmetric Optical Modulation, are analyzed in context with alternative highly efficient modulations schemes, such as generalized space shift keying.